Tuesday, September 20, 2005

Harry Potter Inheritance

The following is a letter published in Nature from three PhD scientists at the Murdoch Children’s Research Institute. This is what happens when incredibly smart people get together and drink waaaayyyy too much.


We are bombarded with news of genetic discoveries on an almost daily basis, but people without a formal knowledge of heredity and genetics can have difficulty in deciphering and applying this information. Education and debate across all ages would undoubtedly help, but how can we teach children these concepts?

We believe that successful lessons for younger children can be achieved using analogies of direct interest and relevance. Most children are familiar with J. K. Rowling's stories about the young wizard Harry Potter (whose latest exploit, Harry Potter and the Half-Blood Prince, was published by Bloomsbury in July). They are set in a world like our own, but populated by a minority of people with supernatural powers (wizards and witches) and a majority of people without (muggles).

Wizards or witches can be of any race, and may be the offspring of a wizard and a witch, the offspring of two muggles ('muggle-born'), or of mixed ancestry ('half-blood').

This suggests that wizarding ability is inherited in a mendelian fashion, with the wizard allele (W) being recessive to the muggle allele (M). According to this hypothesis, all wizards and witches therefore have two copies of the wizard allele (WW). Harry's friends Ron Weasley and Neville Longbottom and his arch-enemy Draco Malfoy are 'pure-blood' wizards: WW with WW ancestors for generations back. Harry's friend Hermione is a powerful muggle-born witch (WW with WM parents). Their classmate Seamus is a half-blood wizard, the son of a witch and a muggle (WW with one WW and one WM parent). Harry (WW with WW parents) is not considered a pure-blood, as his mother was muggle-born.

There may even be examples of incomplete penetrance (Neville has poor wizarding skills) and possible mutations or questionable paternity: Filch, the caretaker, is a 'squib', someone born into a wizarding family but with no wizarding powers of their own.

We believe that, with the use of these examples, the concepts of mendelian genetics can be introduced to children as young as five, and then built on by gradually introducing specific terms such as 'gene' and 'allele', and relating these to chromosomes and DNA. At every stage, the children's familiarity with the Harry Potter characters can be used as a hook to engage them in discussing concepts of heredity and genetics.

Great idea, no? However, these genetics geniuses made a mistake. It took three other PhD’s, or maybe their 5 year old children, to correct them. Can you figure out what it is?